Dubbing

The camerawork in this is great, but much of the music was essentially drowned out by the screaming of the crowd, so several months after the performance, the Beatles went into a London cinema recording studio and re-created most of the concert "live", and that's what we're listening to here. Interestingly, they didn't re-do "Act Naturally", so the producers had to take the studio version off of the HELP! album and use it instead, although the studio and live versions don't entirely sync up; there's a moment when you can hear Ringo singing, but his mouth on-screen is closed shut!